Specify the horizon that is to be assumed by the show command.

Arguments:

Elevation elevation

The elevation angle of the desired horizon.

Example:

The following example tells subsequent invokations of the show command to compute the rise and set times of sources, for an elevation of 43 degrees.

 horizon 43.0

Context:

In addition to showing where a source is positioned, the show command displays the times at which the source next rises and sets. Until the horizon command has first been run, the rise and set times are computed assuming a local elevation of 0.0 degrees. The CBI has a minimum elevation of 42 degrees, so this gives a false impression of when the source will be visible. The horizon command is thus normally called from the $CBI_DIR/conf/cbicontrol.init script to specify an elevation that matches the mimimum elevation of the telescope.